revaxarts said
My upcoming WP pluign supports Retina displays. I mainly had to iclude 2 sizes of all images and a little bit of CSS . The menu icon was a little bit tricky though.
To target Retina displays with CSS I use

@media only screen and (-webkit-min-device-pixel-ratio: 1.5),
only screen and (-o-min-device-pixel-ratio: 3/2),
only screen and (min--moz-device-pixel-ratio: 1.5),
only screen and (min-device-pixel-ratio: 1.5) {
//your CSS here
}

Detecting Retina with JS:

var isRetina = window.devicePixelRatio > 1;

Just little typo fixed up above from 32 to 3/2 for opera targeting.

It’s nice to give your users an option to upload a ‘retina’ logo. You don’t really need to use a fixed area though, just a fixed height or width should work.